Low power and Lossy Network Border Routers (LBRs) such as, e.g., Field Area Routers (FARs), are routers in a computer network (e.g., a Smart Grid) that are installed in the field at various locations to provide communication between nodes of a local computer network (e.g., a field area network (FAN), personal area network (PAN), etc.) and a central or wide area network (WAN). For example, on the “southbound,” FARs may connect Low power and Lossy Network (LLN) domains that comprise a large number of devices (e.g., sensors and actuators) using low power shared-media links, such as wireless or powerline communication (PLC) links. On the “northbound,” FARs communicate with the Utility Control Center using various backhaul technologies such as 2G, 3G, LTE, WiMax, etc., as will be understood by those skilled in the art. In other words, FARs often act as “root nodes” through which all of the traffic transits between the local network to a control center, and thus play a critical role in the network infrastructure.
In a typical FAN, such as one configured for Advanced Metering Infrastructure (AMI) applications, a FAR may communicate with thousands of end-points (nodes) on the downlinks (access network) using an IP-based mesh network. New mesh formation may happen frequently, for example, when a FAR is impacted by a failure or a software upgrade, or when a node migration occurs. A mesh network is typically secured using group-based encryption keys, and these keys are initially forwarded to the mesh nodes using a known authentication scheme. It has been observed that new mesh formation in an LLN with an intermittent backhaul connection may be significantly delayed, largely as a result of the authentication process.